Isn't diaper making fun?! If you haven't already, join the yahoo group sewyourowndiapers -- there are lots of informative mamas there. I would also suggest, that since you don't have an ittie bittie to test the dipes on, that you buy a pattern -- there's a better chance that the dipe will fit right, kwim? Or perhaps you could buy a dipe you like tear it apart & duplicate it -- but remember not to sell them afterwards!

:LOL
The only pattern I bought, poopockets (one sized dipe) & side-snapping poopockets, had very clear instructions on what supplies you needed & how much yardage, etc. Everyone has their opinion of what fabrics are best, but most agree that hemp is unbeatable. I wouldn't buy regular terry cloth, after having worked with it when making recycled material dipes -- it's too bulky for the amount of absorbancy (sp??) you get.
I don't use anything on the inside of the dipes -- just the absorbant materials, because I prefer to only have natural materials against my ds's privates. If you want to make aio's I would buy a little of both fleece & pul to see which you prefer. You can also use wool, but those would be "almost" in ones...
Of course, if you've used cloth with your older children, you may have preferences already!
Anywho...hope that helps! I have to get sewin' some newborn dipes soon myself!